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RE: simon:entity (or Identifiable)

From: Myers, Jim <MYERSJ4@rpi.edu>
Date: Fri, 15 Jul 2011 15:48:09 -0400
Message-ID: <B7376F3FB29F7E42A510EB5026D99EF2054000AB@troy-be-ex2.win.rpi.edu>
To: Jim McCusker <mccusj@rpi.edu>, <public-prov-wg@w3.org>


> -----Original Message-----
> From: Jim McCusker [mailto:mccusj@rpi.edu]
> Sent: Friday, July 15, 2011 1:46 PM
> To: Myers, Jim
> Cc: Luc Moreau; public-prov-wg@w3.org
> Subject: Re: simon:entity (or Identifiable)
> 
> On Fri, Jul 15, 2011 at 12:06 PM, Myers, Jim <MYERSJ4@rpi.edu> wrote:
> >>
> >> Being able to describe what the entity "looks like" at the time the
> >> provenance was recorded.
> >>
> >> My understanding was that a BOB was something like a named graph,
> > graph
> >> literal
> >> (http://webr3.org/blog/semantic-web/rdf-named-graphs-vs-graph-
> >> literals/),
> >> or information artifact similar to iao:Dataset. The Bob would then
> > have
> >> content that described, in some way, the entity in question.
> >> Hence the Bob being a description of an entity's state.
> >
> > Do you distinguish 'description of an entity' from 'description of
an
> > entity's state'? I get the sense that you are not using state in the
> > same sense of 'a more stateful view of' that is driving the
discussion
> > of entity versus entity-state in the IVPof debates.
> 
> Any description of an entity will occur with an entity in a particular
state, and
> so two are the same.
> 
What does particular state mean? Are you in one particular state as long
as you are 'alive'? I don't think there's an issue that some aspects of
state are always part of a Bob. The questions from the IVPof discussions
are more about whether a bob with minimal state is a different type of
thing than a bob with 'more state'.  I think that since 'all bobs have
some state' for you, you're not talking about this problem and we have
an overloaded words problem again.

> >> If it is possible to know, there should be assertions on the BOB
> > itself that say
> >> which entity the BOB is describing. Ideally, this is a URI of
> > something that's
> >> referenced within the BOB.
> >
> > I'm hoping someone will chime in on this - I agree we need to
connect
> > the idea of a bob with the entity, but I could see implementing that
> > as a link (as you say) or by saying that my entity's class is a
> > subtype of Bob (hence there's only one URL for the Bob and the
entity).
> 
> But that's clearly wrong, since Bobs only describe the state of an
entity at one
> point/span of time and context. If the same entity is observed again,
and a
> new Bob is created that describes the state differently, then there's
nothing
> to tie it down. I'm guessing that by saying there is no referable
entity outside
> of the Bob, then you can just make Bobs all the way down. But there
would
> be no grounding to non-provenance resources in this case.

I'm not sure we're on the same point. There can be a bob for "Jim in the
alive state", and one for every time there's a "standing Jim' that
engages in a 'sitting' process execution to create a  'sitting Jim/Jim
in a sitting state' bob. All of these bobs have some relation to the
real Jim and to any richer digital description, e.g. your
http://tw.rpi.edu/instances/JamesMcCusker resource. (The 'sitting-Jim'
and 'standing-Jim' bobs are all IVPs of "Jim in the alive state".)

All I was trying to say is that at the implementation level, I think I
have the choice to either use the identifier for your resource directly
in provenance statements (in which case I have to be able to treat it as
a subtype of bob), or I can create an ID for the Jim bob which has a
link to your resource. 

I'm not sure where you're going with the Bob's all the way down idea. I
don't think observation causes new bobs to appear, but I agree that a
new bob (e.g. bobs that are instances of  'sitting-Jim' and 'standing
Jim') is created for every process execution ( if you sit twice, there
are two distinct  'sitting Jim' bobs, and it is the act of sitting that
creates these bobs, not the existence of a witness who observed them -
the creation time of the bob is when the sitting process occurs, not
when the observer sees you sitting two minutes after that). I see the
sense that these bobs are IVPs of 'alive-Jim' as being completely
orthogonal to the fact that there's an entity or entities in the
semantic web and/or real world that these bobs correspond to.

> 
> The Bob is the description of something based on its state, the Entity
is that
> something. A description of a thing is not the thing itself.
> Within the context of information systems, one can say that
> http://tw.rpi.edu/instances/JamesMcCusker is me. If you were to
download
> the RDF from that URL that would contain a description of me within
the
> context of RPI. The graph literal behind
> http://tw.rpi.edu/instances/JamesMcCusker is one description (that can
> change over time), and can be given an identifier using a graph digest
[1],
> guaranteeing that we always talk about the same graph. But that graph
is not
> me, even though the URI that returns it stands in for me in the
semantic
> web.

Yes - no objections. We're saying the bob is you in the provenance
model, but it is connected to an entity which is you within the context
of the semantic web. The bob is really just a description of you, and
the semantic web resource is just a description as well.

I think two things are happening as we think about these connections.
One - the things we can express about you/your state get richer as we go
from provenance model to semantic web to reality. Two, we're
encountering issues ala the IVPof relationships within the provenance
model. The bob for some instance of 'hungry-Jim' is not the same
dimensionality as the semantic web resource which in turn is lower
dimensional that the physical/real you.


> 
> [1]
>
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1.2187&rep=rep
> 1&type=pdf
> 
> Jim
> --
> Jim McCusker
> Programmer Analyst
> Krauthammer Lab, Pathology Informatics
> Yale School of Medicine
> james.mccusker@yale.edu | (203) 785-6330
> http://krauthammerlab.med.yale.edu
> 
> PhD Student
> Tetherless World Constellation
> Rensselaer Polytechnic Institute
> mccusj@cs.rpi.edu
> http://tw.rpi.edu
Received on Friday, 15 July 2011 22:26:34 GMT

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